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Texas Instruments



Texas Instruments products are most commonly encountered in keyboards and other electronic equipment in the form of 7400-series integrated circuits. This is a family of TTL (transistor–transistor logic) chips, which are building blocks for logic circuits. Originated by Texas Instruments, many other semiconductor manufacturers have produced 7400-series chips.

Texas Instruments also made keypads as well as keyboard encoders. Full-size keyboards with their branding have been found, sourced from other manufacturers such as Alps Electric, and they appear to have been an early customer for Alps KCL/KCM series.

Keyboard encoder ICs

Texas Instruments are known to have produced two models of single-chip keyboard encoders, TMS 5000 and TMS 5001.

Model Keys Modes Bits/key Rollover Output Data Notes
TMS 5000 90 4 ASR-33 The details are only known from a single advertisement
TMS 5001 90 4 10 NKRO/N-key lockout Parallel ASCII typewriter and bit-paired
The four encoding options are likely to be separate parts

TMS 5000

Little is known about the TMS 5000. It is mentioned in US patent 3974575 filed in June 1974. An advertisement in Popular Electronics in 1977 for the “TMS-5000” (specifically TMS 5000 NL) indicates that it is a quad-mode 90-key encoder with ASR-33 output. The advertisement also mentions the “ZA 8010 C” marking as seen on the TMS 5000 NC encoder in a Clare-Pendar–manufactured Texas Instruments Silent 700 keyboard, suggesting that the chips being sold are surplus parts. However, the Clare-Pendar keyboards used TMS 5000 NC. (“NC” and “NL” are both plastic IC packages, contrasted with the ceramic “JC” and “JL”, but the meaning of “C” and “L” is not defined.)

TMS 5000 is said to be “Compatible with Reed and Mechanical Switches”, a phrase used verbatim in the TMS 5001 specifications.

TMS 5001

By comparison, TMS 5001 is much better documented. The preliminary specifications for TMS 5001 NL are give in the Semiconductor Memory Data Book for Design Engineers from 1975. There is no indication of how TMS 5001 differs from TMS 5000. This is also a 90-key quad-mode encoder, with 10-bit output codes. Both N-key rollover and N-key lockout are offered. In N-key lockout mode, the output code is latched onto the data lines and remains so until the key is released and the next key is pressed. In N-key rollover mode, the output code is only present on the data lines briefly after the key is pressed, in order to allow the encoder to continue looking for more keys to report.

The documentation lists four output types: ASCII in both bit-paired and typewriter modes, ASR33, and Baudot paper tape punch code. With its 3600 bits of ROM and lack of any form of encoding selector, it would seem that these are separate pre-built masks, and the customer is expected to specify their choice of mask during ordering. Separate part numbers for these four variants may exist, but the databook did not list them.


Texas Instruments filed US patent 4354068 “Long travel elastomer keyboard” in February 1980, which is very early patent for full-travel rubber dome over membrane keyboards. Even if such keyboards did go into production, Texas Instruments likely did not produce them for long, as they outsourced their keyboards from other manufacturers.

Their 914 terminal keyboards and 911 Keyboard were made instead by Micro Switch, being SW Series and SD Series respectively (the examples are dated from 1975 and 1982).

Texas Instruments are notable for some rare Alps-made keyboards:

Keyboards for the TI-99/4A were sourced from a variety of manufacturers, with the known vendors being Alps, Futaba/Sejin, General Instrument, Mitsumi and Stackpole.

The Texas Instruments TravelMate LT286/12 keyboard was produced by Hi-Tek using a rare switch type.



Klixon is a type of metal dome switch produced by Texas Instruments, used for keypads.